1. Field of the Invention
The present invention relates to an improvement of a rolling bearing with seal comprising: an inner race; an outer race surrounding the inner race; a large number of rolling members arranged in an annular form and interposed between the inner and outer races; and a pair of annular seal members disposed between the inner and outer races in such a manner as to cover opposite sides of a group of the rolling members, wherein an attachment bead to be fixed to the outer race is formed on an outer periphery of each of the seal members, and a seal lip rotatably and slidably being in close contact with an outer peripheral surface of the inner race is formed on an inner periphery of each of the seal members.
2. Description of the Related Art
Such a rolling bearing with seal is, as disclosed in Japanese Patent Application Laid-open No. 2004-263734, interposed between a partition wall, between two chambers having different internal pressures, and a rotary shaft penetrating the partition wall. The rolling bearing with seal is capable of preventing pressure shift between the two chambers while securing smooth rotation of the rotary shaft.
Meanwhile, in the seal member of the rolling bearing with seal described in Japanese Patent Application Laid-open No. 2004-263734 above, the seal lip being in close contact with the outer peripheral surface of the inner race is formed in such a frusto-conical shape as to extend toward an outer side of the inner race while extending inward in a radial direction of an inner race. For this reason, when a large negative pressure is generated in the chamber which the seal lip faces, the negative pressure acts on an outer peripheral surface of the seal lip with the frusto-conical shape, trying to float up the seal lip away from the outer peripheral surface of the inner race. This weakens a sealing pressure of the seal lip against the inner race, possibly causing grease inside the bearing from flowing out.